P. Saich, P. Lewis, M. Disney and G. Thackrah, 2001. Comparison of Hymap/E-SAR data with models for optical reflectance and microwave scattering from vegetation canopies, in proc. Third International Workshop on Retrieval of Bio- and Geo-Physical Parameters from SAR data for Land Applications, Sheffield, September 2001.

Research

My research is more generally in the interactions of radiation (predominantly at optical wavelengths) with the land surface. In particular I am interested in how radiation interacts with vegetation, how we can model and understand this interaction and how we can exploit it to quantify and understand the terrestrial biosphere, particular relate to the carbon cycle - how plants take up and release carbon, naturally, in response to changing climate and under an increasing range of anthropogenic disturbances (eg fire, land use change, agriculture, deforestation and degradation etc). Satellites allow us large-scale but very indirect observations of surface biophysical properties, particularly the extent and dynamics of vegetation. Much of my research effort has been directed at new ways of exploiting observations of this sort to provide quantitative estimates of these things that are consistent with our understanding of climate carbon cycle models and observations. The image below sums up our aims - this shows an area of temperate rainforest on Fraser Island, Northern Queensland, Australia. The variety of structure (shadows, texture) and variations in leaf colour (to do with chlorophyll and water content) is very striking. My aim is to understand and exploit this 'signal' much better than we can do currently, for all sorts of applications that rely on knowing the state of forests like this.

I've continued to work with 3D models over the last few years, as they give us an unprecedented level of detail with which to model radiation interacting with the surface - and this is our satellite signal. Faster, cheaper computers mean we can use these models in ways we never could even a few years ago. I have worked with on the librat modelling software, which we have developed over the years into a powerful modelling tool, which we make freely available. We have used the tools for a range of applications and projects, including exploring lidar signals, modelling fire impacts and for benchmarking and testing simpler models, as part of the ongoing Radiative Transfer Model Intercomparison (RAMI) project; librat is one of the 'credible models' used in the RAMI online model checker. The librat wiki page contains some documentation on the software along with a list of some of the student projects and publications arising from librat over the years. We are always amenable to further collaborations using librat, so drop us an email.

A recent project which demonstrates an application of my 3D radiative transfer work, funded by the European Space Agency Support to Science Element, is 3D Veglab. The project, led by Felix Morsdorf at the University of Zurich, has developed an open toolbox of 3D models and simulation tools, including our librat modelling software. A nice movie (produced by Felix and the UZH group) demonstrating how the toolbox was put together is shown below.

This work addresses the requirement to be able to measure biomass, particularly in the tropics, more consistently, and ideally, independent of other field-based and satellite-derived measures, all of which rely on empirical (allometric) relationships between trunk diameter, height and volume (and hence biomass). But you can also scan elephants!

In early 2014 we obtained a new Riegl VZ-400 TLS instrument using NERC funding. WE will be using this instrument to scan forests across the world, but our first work is with Forest Research (UK Forestry Commission) at their experimental forest in Alice Holt, Surrey. We are scanning leaf-off and leaf-on conditions in a plantation oak woodland, before destructively harvesting the trees to weigh them, providing validation of our 3D reconstructions from the lidar. A first fly-through of these data is here:

My funding comes from a variety of sources, but primarily NERC and ESA.

Data funding/Science Teams:

2007+: ESA PI (ABACUS project)

2000+: CHRIS-PROBA

2000+: Multiple NERC ARSF acquisitions

Impact

Impact

My research in recent years has involved funding and collaboration across a range of sources and disciplines, including UK research councils, NASA, European Space Agency (ESA), EU, as well as NGOs and other organisations. The research has been part of work contributing to provision of information on global environmental processes, particularly vegetation and the land surface more generally, that has been used nationally and internationally to inform government and agency activities. Examples of this include: development and testing of global satellite datasets such as albedo, provided by NASA and ESA and used by a wide variety of government, NGO and other users such as the Met Office and ECMWF; development of new methods for monitoring change (particularly fire impacts) and forest carbon stocks eg for NGOs, African National Parks agencies (Gabon, S. Africa). Work on albedo has featured in the IPCC AR4 (2007) and AR5 (2013). I have led various consultancy projects through UCL, working with a range of industrial partners including via collaborative PhD research funding, enabling development of new remote sensing methods and instrumentation, particularly lidar. I have sat on government panels assessing government funding in environmental science for a range of agencies including NERC, NASA, ESA, the Environmental Protection Agency of Ireland and the Australian National Research Council, among others.

Outreach

I have participated and/or led a number of activities to bring the work I do to the wider public, as well as trying to promote interest in science topics more generally. I have been involved in two Royal Society Summer Exhibitions, contributed material on forests, fire and carbon to the NERC representative (Prof. Shaun Quegan) presenting examples of NERC-funded environmental science to the Parliamentary Committee on Science and Technology. I have been involved in in Network for Calibration and Validation of Earth Observation Data (NERC Knowledge Transfer project) and wider international CEOS Working Group on Calibration and Validation activities (e.g. lead of core MODIS validation site in UK, http://landval.gsfc.nasa.gov/coresite.php?SiteID=6). I regularly give lectures to schools across a range of age groups (from 11 to 18), focusing on topics of carbon, forests and climate change. I have given live presentations to children via virtual learning environments (see

Second Year

GEOG2021 Environmental Remote SensingConvenor: Prof. P. LewisA 2nd year introduction to remote sensing, covering how we acquire data, information extraction and various applications of remote sensing. The course is split between lectures and practicals and forms the usual requirement for 3rd year course, GEOG3010. Taught jointly with Prof. P. Lewis Here is the course webpage.

Third Year

A 3rd year course following on from GEOG2021, introducing the fundamental concepts of how radiation interacts with the Earth's surface at a range of wavelengths, the laws and principles we use to exploit this interaction, and examples of remote sensing applications including LIDAR and RADAR remote sensing of vegetation and the terrestrial carbon cycle. Contains a practical element of programming to handle simple image analysis, again building on GEOG2021.